Thursday, October 2, 2014

Dinosaurs, Pterosaurs And Other Saurs -- Big Differences

Any chiefly terrestrial, herbivorous or carnivorous reptile
of the extinct orders Saurischia and Ornithischia, from the Mesozoic
Era, certain species of which are the largest known land animals.

That’s a decent description of a dinosaur, but it’s not the scientific definition.

Paleontologists don’t group species together according to when and
where they lived, but based on shared characteristics, usually
anatomical features seen in fossils. Dozens of features distinguish
dinosaurs from other reptiles, such as bones of the lower arm being
longer than the upper arm. When Paleontologists combine and compare such
characteristics between various reptiles, they can create a tree of
evolutionary history that reveals the relationships between different
groups.

Several groups of prehistoric creatures are often mistaken for
dinosaurs, even though evolutionary trees show that they’re distantly
related. One group doesn’t even consist of reptiles. To help you tell
extinct reptiles apart, here is a simple guide to the major features of
dinosaurs and ‘other saurs’, arranged in order of when the animals
appeared millions of years ago (MYA).